The PROMIS of Measuring Patient-Reported Outcomes

A pre-meeting session at the annual meeting delved into the benefits and challenges of “PROMIS Versus Legacy Data Instruments” in collecting patient-reported outcomes (PROs) in rheumatology.

Clifton O. Bingham III, MD, of the School of Medicine at Johns Hopkins University, said PROs can be used in clinical trials, observational studies, and clinical practice. Focusing on clinical practice, he said that the instruments practitioners use to measure PROs must be reliable, precise, fit for the purpose (e.g., more precision may be needed in clinical practice than in group studies), meaningful, actionable, and feasible.

In preparation to compare the Patient-Reported Outcomes Measurement Information System (PROMIS) tool to legacy instruments, Dr. Bingham defined legacy data instruments as tools that have been traditionally used for measurement in a given condition. In rheumatoid arthritis (RA), he said most composite disease activity indices do not include all outcomes of concern to patients. “Things we currently measure the most, pain and function, are important, but other outcomes like fatigue have been cited as important to patients, and we don’t currently measure them,” he said.

Dr. Bingham specifically discussed the strengths and weaknesses of the global visual analog scale (VAS), pain VAS, Health Assessment Questionnaire Disability Index (HAQ-DI), RAPID-3, 36-Item Short Form Health Survey (SF-36), and Rheumatoid Arthritis Impact of Disease (RAID).

VAS and numerical rating scales, although commonly used and simple to administer, may not adequately reflect a complex construct, and they may not be interval scales of measurement, he said. Although the HAQ-DI is the gold standard for physical function in trials and defines a minimally important difference (MID) for improvement, he continued, the instrument contains 20 questions, scoring is more difficult, content relevance and interpretation are troublesome for patients, and it may not provide enough information about patients with relatively good performance.

The RAPID-3 is easily deployable, responsive in trials, and has established thresholds. But the score only reflects core domains, not all domains that patients have described as important. Dr. Bingham also reviewed the SF-36, which can be used across multiple disease states, is generic about health-related quality of life (QOL), and is responsive in clinical trials. However, the tool requires complex scoring and has a fee. Additionally, some of the concepts are “nebulous,” Dr. Bingham said, making it difficult to define actionability.

Finally, he discussed RAID, which was derived from patients and what they identified as important, is easy to administer, and has simple scoring, but it has not been widely deployed in trials and observational studies, and responsiveness and minimally importance difference have not yet been well defined.

Dr. Bingham then discussed PROMIS, which was developed to evaluate health-related QOL across physical, mental, and social health. It measures physical function, anxiety, depression, fatigue, pain interference, sleep disturbances, and satisfaction. Item banks reflect health domains applicable across disease states, and scales are reported as T scores. PROMIS uses computer-adapted testing and must be embedded in the computer system.

A review of the literature has shown that the tool is highly responsive in measuring treatment effectiveness over time in individual patients with RA, a population particularly relevant to this meeting. Researchers also have started to use PROMIS to track fatigue in clinical trials of rheumatic conditions, including RA and systemic lupus erythematosus.

In conclusion, Dr. Bingham stressed that tools that measure PROs should reflect areas of health that are most important to patients. They should perform well in clinical practice and allow actionable results. He believes that PROMIS represents an emerging system to measure PROs that may be applicable in multiple settings using a common metric.